PROJECT SUMMARY ? Pulvinar Neuro LLC, FROHLICH Transcranial current stimulation is a form of non-invasive brain stimulation that has recently become a key tool in human neuroscience research and has emerged as a potential treatment strategy for psychiatric disorders such as depression and schizophrenia. Yet, many questions about TCS remain unanswered and its clinical potential has not yet been delineated. We believe a key reason for this is that current TCS research devices do not have the required features for double-blind, placebo controlled studies of targeted stimulation waveforms. The objective of this proposal is to develop the XCSITE 200, a transformative TCS research device which will build upon our XCSITE platform. The XCSITE 200 will allow the study of more targeted stimulation waveforms that carry the promise of increased efficacy in terms of target engagement and behavior outcomes. In addition, XCSITE 200 devices will be managed via the cloud and thus enable cheaper and more effective administration of large, multi-site studies, which are essential in order for the technology to reach FDA clearance. In this Phase I project, we propose to implement custom-waveform and feedback stimulation in XCSITE 200 as well as perform extensive testing both at the bench and in a human pilot study (Aim 1) and to finalize and bench-test the cloud-based device and study management infrastructure (Aim 2). Quantitative milestones for both proposed aims are defined based on component and systems test benchmarks. The development of XCSITE 200 will enable the next generation of large-scale TCS studies with individualized and adaptive stimulation strategies targeting specific brain activity patterns to investigate their causal role in behavior and treat psychiatric disorders caused by altered brain network dynamics (e.g., depression and schizophrenia).